Throughout the battery from a single cell to a complete pack there are many different materials. Hence it is important to look at those in terms of their characteristics and application in battery design.
This page will be arranged A to Z so that you can quickly scan down and find the appropriate section.
1,3,2-Dioxathiolane 2,2-Dioxide (DTD) – used as an electrolyte additive to reduce the initial capacity loss of the battery, reduce the battery expansion after high temperature and improve the battery charge-discharge performance and cycle times.
3-phenyl-1,4,2-dioxazol-5-one (PDO) – shown by Jeff Dahn’s group as an electrolyte additive that improves high temperature storage and cycle life of nickel content cells.
Adhesives
A wide range of applications within the battery pack from binders within active layers to adhesive based seals used in pack enclosures.
Aerogel – synthetic porous ultralight foam material derived from a gel, in which the liquid component for the gel has been replaced with a gas. Possible uses in battery packs based on it’s thermal insulation properties.
Aluminium
Used in electrical busbars, cell cases, module housings and for pack cases. Hence a number of different grades of aluminium based on the requirements from electrical resistance, thermal conductivity, strength and corrosion resistance.
Carbon Black
An electrically conducting agent that enables the formation of the electrical wiring within an electrode. It has typically been specified by loading, surface area and subsequent powder or electrode resistivity.
Carbon Nanotubes
Added to both anodes and cathodes to improve electrical and thermal performance, also add mechanical stability. Can be an enabler for Si anodes.
Carboxymethyl Cellulose (CMC) – used as a binder and as a thickener, particularly in anodes. Refining Carboxymethyl Cellulose.
Cobalt – used in the active materials for battery cathodes. A huge amount of work to reduce and remove this element based on cost and serious ethical sourcing and refining issues.
Copper
HV and LV Busbars, electrical tracks, connectors and for some anode current collectors, here ~10µm thick.
Dielectric Coolant – an array of oils and synthetic liquids that are dielectric and hence prevent or quench electric discharge. There are single-phase and two-phase dielectrics that give a number of options for submersing the cells directly into the coolant. We have assembled a list of key dielectric parameters required for battery cooling: What are the key parameters for dielectric fluids as used in a battery pack?
Diethyl Carbonate (DEC) – Carbonate solvent used in the electrolyte, chosen for its low viscosity and good low-temperature performance.
Dimethyl Carbonate (DMC) – Low-viscosity carbonate solvent used in the electrolyte to improve ionic conductivity. The lowest-viscosity and lowest-cost of the three linear carbonates, but also the lowest-boiling, which leaves it most prone to decomposition and gassing as temperature rises.
DMVC-OTMS – incorporation of DMVC-OCF3 and DMVC-OTMS as electrolyte additives in the VC scaffold leads to the creation of a flexible and robust SEI on the Si–C anode.
DMVC-OCF3 – electrolyte additive that improves the creation of a flexible and robust SEI on the Si–C anode.
Ethylene Carbonate (EC) – Carbonate solvent used in the electrolyte, forms a stable SEI on graphite anodes.
Ethylene Glycol – organic compound used as a coolant, normally mixed 50:50 with water and then flows through isolated coolant plates that the cells interface with.
Ethylene Propylene Diene Monomer (EPDM) – Synthetic rubber used as a gasket/seal material for pack enclosures, valued for weather and ozone resistance.
Ethyl Methyl Carbonate (EMC) – Carbonate solvent used in the electrolyte, valued for its balance of viscosity and stability. An asymmetric molecule that sits between DMC and DEC: usefully low viscosity combined with a wider liquid range than DMC. That balance is a large part of why EMC has become the default linear carbonate in most modern commercial cells.
Fiberglass – Glass-fibre reinforcement used in structural brackets and insulating carriers for strength-to-weight benefit.
Fluoroethylene Carbonate (FEC) – used as an electrolyte additive in lithium-ion and sodium-ion batteries to improve performance and cycle life.
Glass-Reinforced Epoxy (FR4) – Rigid composite laminate used for PCBs and electrically insulating structural parts within the pack.
Graphite
An amorphous form of carbon, made of carbon atoms bound hexagonally in sheets. It is used as a thermal-insulating electrical-conductor, as a nuclear-reactor moderator and as a self-lubricant. In lithium ion batteries it is used as the anode.
Hilumin – an electro nickel-plated diffusion annealed steel strip for battery applications where low contact resistance and high corrosion resistance is required. Trademark of Tata Steel.
Ionic Liquids – are salts that are molten at, or close to, room temperature, built from bulky, asymmetric organic cations (imidazolium, pyrrolidinium, piperidinium) paired with fluorinated anions such as TFSI or FSI. Because the entire electrolyte is composed of ions rather than a molecular solvent carrying dissolved ions, it has negligible vapour pressure and does not sustain a flame.
Iron – Key active material in LFP (lithium iron phosphate) cathodes, valued for low cost, thermal stability, and absence of cobalt.
Lithium
Lithium is a a soft, silvery-white alkali metal. Atomic number of 3 and symbol Li.
Lithium Bis(oxalate)Borate (LBOB) – one of the most common film-forming electrolyte additives used in lithium ion batteries.
Lithium diFluoro (dioxalato) Phosphate (LDFDOP) – also called as lithium difluoro(bisoxalato)phosphate (LiDFBOP)
Lithium diFluoro(oxalate)Borate (LDFOB) – used as thermal stabilizing and solid electrolyte interface (SEI) formation additive for lithium-ion battery.
Lithium Difluorophosphate (LDFP) – electrolyte additive used in conjunction with PDO to improve cycle life.
Lithium tetraFluoro(oxalato)Phosphate (LTFOP) – used to improve the life of mesocarbon microbead (MCMB)/ NCM cells for high power applications. The addition of LTFOP in the electrolyte increased the initial impedance but lowered the impedance growth rate during cycling.
Manganese – used in the active materials for battery cathodes.
Silicate minerals used in a thin sheet form as a thermal barrier in battery pack designs to contain thermal runaway.
Nickel
Pure nickel is malleable and ductile, and is resistant to corrosion in air or water, and hence is used as a protective coating on busbars or just at busbar joints.
Niobium – lots of interest as a substituted element into Nickel rich NMC chemistry to improve stability and hence reduce degradation.
N-Methyl-2-pyrrolidone (NMP) is an organic solvent used heavily in lithium ion battery fabrication, as a solvent for electrode preparation.
Phase Change Material – using the energy required for a phase change in a material to limit the maximum temperature of a battery cell is an interesting approach to thermal management. Within this also we need to look at the materials that are typically available and used.
Plastics
A vast array of plastics are used across the battery pack for structure, sealing, isolation and protection.
Polyacrylic Acid (PAA): used as a binder in silicon anodes due to flexibility.
Polyethylene (PE) – Microporous membrane used as a separator between anode/cathodes.
Polyethylene (PE) Foam – Closed-cell foam pad used for cell/module compression and light thermal insulation.
Polypropylene (PP) – Microporous membrane used as a separator between anode/cathodes.
Polytetrafluoroethylene (PTFE) – used in the past as a binder for both anodes and cathodes due to its high chemical and thermal resistance.
Polyurethane (PU) Foam – Compressible foam pad used between cells or modules to absorb swelling and take up tolerance.
Polyvinylidene Fluoride (PVDF) – widely used as a binder, especially for cathodes, known for its good mechanical, chemical, and electrochemical properties.
Silicon – High-capacity anode material (theoretical capacity ~10x graphite) increasingly blended with graphite, though prone to swelling and requiring binder/additive support to manage expansion.
Silicone Rubber – Used as a gasket/seal material in pack enclosures and cell compartments, chosen for wide temperature stability and flexibility.
Sodium
A soft, silvery coloured metal which, like other members of the alkali group of metals, is extremely reactive. As for the other members of the group, it can be prepared by electrolysis of the fused halide or hydroxide.
Steel – Structural material for pack enclosures, brackets, and end plates, chosen for strength and crash performance where weight is less critical than aluminium.
Styrene Butadiene Rubber (SBR) – commonly used as an anode binder, known for its versatility and electrochemical performance.
TIM – Thermal Interface Material
Normally a silicon based compound loaded with graphite to improve it’s thermal conductivity. The purpose of thermal interface materials (TIM) is to transfer heat between two solid surfaces. In the case of a battery this is normally between the outer surface of the cell case and a cooling plate.
Tin
- Tin Anode – a promising anode material for sodium ion batteries. Theoretical [1] specific capacity = 847 mAh g-1 and volumetric capacity = 6238 mAh cm-3.
V0 Plastics – sometimes used as an abbreviation to describe a plastic that meets the UL94:V-0 certification. The tested material has to self extinguish within 10 seconds on a vertical part allowing for drops of plastic that are not inflamed.
Vinylene Carbonate (VC) – an effective electrolyte additive to produce a stable solid electrolyte interphase (SEI) on graphite anodes, increasing the capacity retention of lithium-ion cells.
See also: Testing